Straight line and chalk line tools have long been used for various purposes to provide a straight line reference, whether by viewing of the tool's line (or string) simultaneous to its extension or by subsequent reference to a mark made by the tool's line after its chalk impression is left on the ground or other surface. Such tools have typically been hand-held devices wherein the line is unwound from a spool within the tool housing by an external force to a point distant the tool. If a chalk line mark is desired, the tool housing is filled with chalk prior to the removal of the line from the tool housing. Once the straight line reference is made with the extended line, or a chalk line is marked on the desired surface, the line is retracted into the tool housing and onto the spool by means of a handle or crank manually driven so as to reel in the line.
One prior art chalk line tool 10 is shown in FIG. 1. The illustrated chalk line tool 10 comprises a housing 12, a spool 14, a crank assembly 16, and a line 18 having a wound end and a free end. The housing 12 is pear-shaped and generally fiat in nature, having an upper and a lower face separated by a continuous wall defining a spool chamber 20 located between the upper and lower face and at one end of the housing, the spool chamber tapering to a thinner neck 22 at the opposite end of the housing. The spool chamber 20 is sized to house the spool 14. Along the neck 22 of the housing 12 is an oblong chalk aperture 24 having a cover 26 slidably coupled to the housing 12 so as to cover and uncover the chalk aperture 24. The chalk aperture 24 provides access to the spool 14 and line 18 located on the interior of the housing 12 such that chalk can be placed within the housing to dust the line. A second aperture, namely a line aperture 28, is located at the end of the neck 22 of the housing 12 through which the free end of the line 18 is passed from the interior of the housing to a point external to the housing. The interior of the housing 12 further includes securing members 30 for securing the upper and lower face of the housing 12 together.
The spool 14 has opposing circular end plates 32 separated by and affixed to a cylindrical axle 34, and is rotatably mounted inside the housing 12 in the spool chamber 20. The crank assembly 16 includes a handle 36 mounted to a crank shaft 38, both of which are external to the housing 12, save for one end of the crank shaft 38, which is immovably affixed to the axle 34. Cranking movement of the handle 36 drivingly rotates the crank shaft 38, which in turn drivingly rotates the axle 34 and the associated end plates 32.
The line 18 is generally made of lightweight string. The wound end of the line is affixed to and wound around the spool 14, on the axle 34 and between the opposed end plates 32, with the line's free end passed out of the line aperture 28. The free end of the line generally has a hook 40 used to facilitate securing of the free end of the line to a stationary object (not shown) when a straight line reference is desired.
In typical operation, chalk is placed into the housing 12 via the chalk aperture 24, after which the cover 26 is closed to prevent chalk from escaping. The free end and hook 40 of the chalk-dusted line 18 is then removed from the line aperture 28 away from the housing 12, unwinding the line from the spool 14. After obtaining the straight line reference, the chalk-dusted line 18 is then retracted into the interior of the housing 12, rewinding the line onto the spool 14 by manually cranking the crank assembly 16, namely by turning the handle 36 and thereby drivingly rotating the spool 14 until the line is again secured on the spool within the end plates 32.
The manually driven crank assembly creates practical disadvantages in the use of existing straight line and chalk line tools. Specifically, existing line retrieval requires expenditure of both time and effort to manually retrieve the line from its extended position external the housing. These disadvantages are accentuated the further the line is removed from the housing. The present invention is directed to overcoming these disadvantages.